Financial Instruments and Fair Value Measurements - Summary of Gains (Losses) From Change in Fair Value of Derivative Instruments Included in Other Comprehensive Income (Parenthetical) (Detail) € in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 EUR (€)	Jun. 30, 2017 USD ($)	Jun. 30, 2017 EUR (€)	Dec. 31, 2016 EUR (€)	Dec. 31, 2015 EUR (€)
Derivative Instruments Gain Loss [Line Items]
Amount received from (paid for) on settlement of net investment hedges	$ 2,500,000	$ 79,800,000	$ 128,200,000
Interest expense reclassified	274,486,000	303,146,000	301,363,000
Debt	9,412,631,000	10,608,294,000
Foreign currency translation gains (losses), net	63,455,000	(135,958,000)	(208,901,000)
Senior notes	6,100,000,000
Forward Contracts
Derivative Instruments Gain Loss [Line Items]
Foreign currency translation gains (losses), net	(17,900,000)	0	10,000,000
Foreign Currency Options [Member]
Derivative Instruments Gain Loss [Line Items]
Foreign currency translation gains (losses), net	(5,400,000)
Designated As Hedging Instrument [Member] | Forward Contracts
Derivative Instruments Gain Loss [Line Items]
Debt	3,600,000,000	3,400,000,000	$ 3,500,000,000	€ 3,100.0			€ 3,200.0	€ 3,200.0
Designated As Hedging Instrument [Member] | Foreign Currency Options [Member]
Derivative Instruments Gain Loss [Line Items]
Senior notes	436,000,000			€ 323.7	$ 645,300,000	€ 500.0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense reclassified	5,400,000	$ 5,500,000
Amount to be reclassified to interest expense, next 12 months	$ 3,100,000